No interest in any subjects at school - am I weird and does anyone else feel the same?

The surprising thing is (and I'm honestly not trying to brag) is that I got 3 A*s (Maths, Textiles and French and an A (Music) in the subjects I took last year for GCSE and am on track to getting my target grades of 5 more A*s and an A this year. However, I have never had any particular interest in any of the subjects I have taken. I find motivation to work through the fact that I want these grades to compensate for depression I have been going through because of family issues, my loss of friends, etc and getting good grades is the only thing that can make me feel better. I'm in year 11 and have chosen my options for next year (Maths, Chemistry, Bioloigy and French) in the hope of maybe going into medicine if I get As, (which is the only thing I can think of doing because they're probably my best subjects), but I don't have any enthusiasm for anything. Don't get me wrong - I can succeed in exams because of extremely high self motivation, but I don't have pion or enthusiasm for anything. How can I overcome this?